Mist eliminator

ABSTRACT

Improved mist eliminator ( 50 ) for use in pulp washers, deinking cells and the like, and methods of use are disclosed. A cyclonic gas/liquid separator ( 50 ) is provided that includes an elongated housing ( 100 ) with a cyclonic flow inducing vane assembly ( 108 ) disposed at a medial location along the length of the housing ( 100 ) to divide the separator ( 50 ) into two tandem cyclonic action zones ( 150, 152 ) of approximate equal volume within the housing ( 100 ). An initial separation is effected in the first cyclonic action zone ( 150 ) followed by final separation in the downstream or second cyclonic action zone ( 152 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

Priority filing benefit of (1) International PCT applicationPCT/US00/18964 filed Jul. 12, 2000, and published under PCT 21(2) in theEnglish language and (2) U.S. Provisional Application Ser. No.60/143,406 filed Jul. 12, 1999.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for the separation of gasand liquid from a flowing mixture of gas and liquid. In particular, theinvention relates to an improved gas/liquid separator of the cyclonicvariety.

In various industrial processes, such as in washing wood pulp, it isadvantageous to draw air from over a reservoir of liquid by means of avacuum provided by a blower intake. The air is usually drawn through theblower and provided under pressure to a portion of an apparatus, such asa pulp washer, to create a region of positive pressure. However, the airdrawn by the vacuum created by the blower may have liquid or solidparticles entrained therein, particularly where the liquid has foam orfroth covering its surface. For proper operation of the blower and theapparatus, it is necessary to separate the entrained particles from theair before the air is taken in by the blower.

Various means of separating a gas from a gas/liquid flow mixture areknown in the art. In particular, separation of liquid and solidparticles from gas streams by cyclonic action is known. For example, acontact-and-separating element of a vortex tray of a liquid-gasmass-transfer apparatus using cyclonic separation is disclosed in U.S.Pat. No. 4,838,906 to Kiselev. Similarly, a dust collection system usingcyclonic separation is disclosed in U.S. Pat. No. 2,393,112 to Lincoln.

In a typical cyclonic separator, a gas mixture having particlesentrained therein is drawn vertically upward. A cyclonic rotation isimparted to the flowing mixture, typically by means of helical or spiralvanes. Centrifugal force causes heavier particles to be forced radiallyoutwardly toward the outer periphery of the flow mixture where theparticles drop back downward under the force of gravity. The gas mixturewithout the heavier particles continues upwardly.

Cyclonic gas/liquid separators may be used in a flat bed wood pulpwasher generally similar in construction and mode of operation to aFourdrinier paper machine incorporating an endless foraminous belt(“wire”), a headbox which delivers the pulp suspension in a pulpingliquor to one end of a horizontally traveling upper run of the wire,successive washing zones along the length of the run, and means at thedownstream end of the run for receiving and removing the resultingwashed pulp. Pulp washers of this type, manufactured by the assignee ofthe present invention in accordance with Ericsson U.S. Pat. No.4,154,644 of 1979, have been notably successful, and the presentinvention was developed to improve the operation and results obtained bysuch pulp washers.

The operation of a pulp washer of this type may be described as beingaccording to the displacement washing principle. That is, once the pulpmat has been formed, it is not rediluted, but simply is subjected torepeated washings by application on top of the mat of washing liquidwith the liquid applied in each washing zone having a lowerconcentration of liquor than the filtrate from the preceding zone. Theliquid applied in each zone enters the mat substantially en masse andthereby displaces the liquid which was carried into the zone in the matand causes it to drain therefrom through the wire.

The mechanical elements of a washer according to the Ericsson patentinclude a hood which encloses the entire apparatus downstream from theheadbox, and a series of receptacles below the operating run of the wirein sealed relation with the hood. In operation, vacuum is applied to thereceptacles, and/or gas pressure is developed within the hood, toaugment the action of gravity in forcing the washing liquid through thepulp mat on the wire. Gases and vapors drawn through the wire into theupper spaces in the receptacles are recycled back to the hood toincrease the pressure differential above and below the wire.

In the pulp washer, a gas/liquid separator or mist eliminator isattached to each of the receptacles at a gas outlet on top of thereceptacle to thereby permit the gases and vapors to be drawn from theflat top receptacles through the mist eliminator to the suction side ofa pump or fan that recycles the gas, in this case air, to the hood.However, entrained within the gases and vapors drawn from the receptacleare particles of mist and foam from the space between the wire and thepulping liquor.

Prior art mist eliminators employing cyclonic separating means have beenused to remove particles of mist and foam from the gas flow before thegas reaches the pump or blower. The typical mist eliminator has acylindrical housing arranged vertically proximate the top of thereceptacle with a vacuum line attached to the top end. The gas inlet ispositioned above the level of the liquor with cyclonic-flow-inducingmeans, typically helical vanes or a swirler, positioned within theinlet. Droplets of mist and particles of foam are hurled radiallyoutwardly by centrifugal force from the gas/liquid flow to drop backdown into the liquor under the force of gravity.

However, in many cases the upward draft of gas through the misteliminator impinges upon the falling, separated liquid droplets. Thistends to retard the separation of undesired droplets of mist andparticles of foam entrained within the gas flow. Thus, incompleteseparation of foreign matter from the gas results. Mist and foamentrained within the gas flow result in a lower pressure differentialbeing developed between the hood and the receptacle, thereby reducingthe efficiency of the pulp washer.

In accordance with the disclosure of WO Publication 98/29179 (of commonassignment herewith) an improved mist eliminator is provided wherein anannular zone is formed in the separator where falling droplets ofseparated water and liquid drain downwardly in the device substantiallywithout resistance from countercurrent flow of gas and liquid.

Although the mist eliminator set forth in the aforementioned WOPublication has proven commercially successful, it was found that insome instances, where dense foams were encountered in the suction box,turbulence was actually increased in the liquid directly beneath theseparator, leading to inefficient separation. Accordingly, there is aneed in the art for a mist eliminator device of enhanced efficiency thatis capable of separating foam components that may exist in the suctionbox.

SUMMARY OF THE INVENTION

These and other objects of the invention are met by the provision of acyclonic separation device wherein two distinct cyclonic action zonesare provided to perform the desired separation of the liquid componentsfrom the gas component. The device includes a generally elongatedcylindrical housing with inlet end and outlet end disposed at oppositeaxial ends of the cylinder. Within the cylinder and at an approximatemedial position along the longitudinal axis of the housing, a swirlimparting vane structure is located. This vane structure forms aboundary defining a upstream cyclonic zone and downstream cyclonicaction zone. The location of the swirl imparting vane structure at anapproximate mid-point along the length of the cylinder contrasts withmany prior art designs where the swirl vanes are located adjacent theinlet end of the separator.

The outlet of the housing is connected to a suitable suction sourcewhich draws the gas/liquid mixture to be separated into the inletportion of the housing, passing generally upwardly through the housingin an upstream to downstream direction. The mixture is first separatedin the upstream cyclonic zone with an additional separation performed inthe downstream cyclonic action zone.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in side elevation showing a horizontal Ericsson-type ofwasher that may incorporate, as a component thereof, an improved misteliminator in accordance with the invention

FIG. 2 is a cross-sectional view taken along the lines and arrows 2—2 ofFIG. 1 and detailing the system location of the improved mist eliminatorof the invention;

FIG. 3 is a partially broken away side elevational view of a improvedmist eliminator in accordance with the invention shown in its positionin a suction box receptacle of the type provided in Ericsson washers

FIG. 4 is a partially broken away side elevational view of the improvedmist eliminator of the invention.

FIG. 5 is a magnified cutaway side elevational view of the swirlimparting vane assembly of the mist eliminator shown in FIG. 4; and

FIG. 6 is a diagrammatic view illustrating use of the improved misteliminator in a recycle pulp deinking cell.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to FIG. 1, there is shown diagrammatically a pulp washingapparatus and system in which the improved mist eliminator of thepresent invention may be advantageously employed. As shown, an endlessforaminous belt 11, usually a wire of woven plastic filaments, istrained around a breast roll 12 at the upstream wire run location, acouch roll 14 at the downstream run location and around drive rolls 16a, 16 b, and tensioning rolls 18 a, 18 b on the return run of the beltto the upstream location. A headbox deposits the pulp suspension to bewashed onto the upstream end of the wire run.

A smooth, foraminous material 22 of low frictional coefficient such as aperforated polyethylene sheet is provided below and in supportingrelation to the upper run of the wire 11. Disposed directly underneaththe sheet and mounted on a frame (not shown) are a plurality ofreceptacles 24 a-24 f. Each of these is, in effect, a suction box,bounded at the top by the perforated sheet. As more fully explained inthe Ericsson patent, the receptacles 24 a-24 f are interconnected andoperated so that they form a series of successive zones along the pathof the wire run comprising a formation zone 28 adjacent the headbox 20and consecutive washing zones 30 a-30 e, the last of which 30 e isadjacent the downstream end of the wire run.

A hood 40 is supported by a frame (not shown) and is positioned inenclosing relationship to the zones 28 and 30 a-30 e. As most clearlyshown in FIG. 2, the hood provides a seal over the receptacles.

Turning back to FIG. 1, each of the receptacles is provided with a drainline 42 a-f. Drain lines 42 c-f communicate with pumps 44 c to 48 f toreturn liquid to shower heads 46 c-f through liquid return lines 48 c to48 f to provide wash water to effect displacement washing of the mat 51of fibers as it travels from the upstream to downstream direction alongthe upper run of the wire 11. Clean water or white water is passedthrough line 252 so that the pulp mat adjacent the couch roll is washedwith relatively clean water. The washed pulp after leaving washing zone30 e exits the device via the assistance of auger 254.

Water drained from receptacle 24 b through drain line 42 b is forwardedto an evaporator tank, with water drained from upstream receptacle 42 aforwarded to a blow tank. Lines 42 a and 42 b are connected via valve(not shown) so that water from line 42 a may be directed to theevaporator if desired and, conversely water from line 42 b could, ifdesired, be channeled to the blow tank.

In simplified form, the apparatus of FIG. 1 serves to evenly distributepulp fed from the headbox onto the moving wire. In the formation zone28, pulp is dewatered from inlet consistency to displacementconsistency, forming a pulp mat. Receptacles 24 a-e serve as suctionboxes under the wire to collect the liquid passing therethrough.

Displacement washing of the mat occurs when the mat goes under theshower where the filtrate from each succeeding washing stage flows ontoand through the pulp. The device depicted in FIG. 1 employs multiplestages of displacement washing, the number of which will depend on thefinish and the washing efficiency required. Dewatering and displacementof shower liquid is a function of the arrangement of the receptacle(suction box) pumps and a blower (explained thereinafter) and the hood.

Turning now to FIG. 2 it can be seen that gas (usually air) is providedto the hood by means of blower 256. Air from each suction box isreturned to the blower via line 258. A pressure differential of betweenabout 1-4″ Hg exists between the hood and the suction box atmosphere sothat this pressure differential provides the driving force for theshower liquid to flow through the mat on the wire.

The hood maintains a seal between the atmosphere and the receptacle. Thegauge value of the pressure in the hood may be positive, zero ornegative depending on the desired washer operation. Filtrate from line48 e is used to provide wash water to shower head 46 e. Filtrate fromreceptacle 24 d is drained through line 42 d where it is pumped by pump44 d to upstream shower head 46 d (See FIG. 1). Line 42 d is providedwith a liquid level control valve 260 operatively associated with pump44 d to control the liquid level inside of the receptacle 24.

Disposed above the liquid level in receptacle 24 d is improvedliquid/gas separator 50 of the invention. Separator 50 is mounted in thereceptacle 24 d. Drainage from the separator passes directly into theliquid in the receptacle 24 d via drain tube 76. A valve 78 controls theflow of gas back to the suction side of blower 256.

Although separator 50 is shown mounted within suction box 24 d, it is tobe appreciated that it could also be spaced closely adjacent to the box24 d. The term proximate as used herein is intended to cover mountedarrangements where the separator is mounted in, contiguous to, orclosely adjacent the receptacle or suction box provided that it islocated upstream from a the control valve 78 that is used to regulatethe fluid flow through the separator device. This disposition contrastssharply with the disposition of the mist eliminators in many prior artEricsson devices in which the mist eliminators were located close to thefan or blower. In these prior art devices a plurality of receptacleswere connected to the mist eliminator via a manifold arrangement andlengthy inlet or feed line to the mist eliminator.

The separator 50 serves to separate foam and liquid from the gas that isto be recycled to the hood by blower 256. Foam and liquid separationhave become critically important as higher soap content pulps such asSouthern Pine Kraft pulps are increasingly used and as washer throughputrates are increased.

Turning now to FIGS. 3 and 4, the separator 50 is shown in greaterdetail. As shown, the separator comprises an elongated cylindricalhousing 100 having as upstream inlet 102 and downstream outlet 104provided at opposite ends along the longitudinal axis of the housing.The separator of mist eliminator is oriented vertically in thereceptacle 30 of the pulp washer with the inlet of the housing spacedabove the pulping liquor level 32.

At the upstream end of the housing, an air straightening baffle 106 maybe securely disposed via welding, brazing, or other attachment means tothe inside of the housing. Spaced above baffle 106 is a cyclonic flowinducing vane assembly 108. The assembly 108 is housed in cylindricalshroud 110, coaxial to the longitudinal axis of the housing. The shroudand vane assembly are secured in the housing by welding of the fourspacer tabs 112 a,b,c,d to the inside wall of the cylindrical housing.

The vane assembly comprises a central rod 114 coaxial with the housingaxis and secured to the rod and shroud are a pair of swirl impartingvanes 116,118. As shown, each of the vanes is in the form of a spiralflight with each flight spanning 270° of the circumference of the rod114. The pitch (length) of each flight is approximately 1.5 times thediameter of the rod. The flights 116, 118 are out of phase with eachother at an angle of 180°. The configuration and spacing of the flightsis not critical provided that they impart a cyclonic swirling motion tothe liquid/gas mixture traveling through the separator in an upstream todownstream direction from the inlet to the outlet.

Fixed to the outside of the shroud and inside of the housing is anannular rim 120 which provides an air tight seal in the area between theshroud and inside wall of the housing. The rim 120 is inclined relativeto the longitudinal axis of the housing at an acute angle of about10-25°; preferable 15°. At the lowest point on the rim (or, stateddifferently, at the point on the rim closest to the liquor level 32) anopening 122 is provided to allow for drainage of liquid. A drain tube124 may be provided in communication with the opening 122 to draindirectly into the pulp liquor. As shown, the tube drain exit 126 isactually submersed in the liquor. Similar to the disclosure of WOPublication 98/29179, the rim and housing define a substantiallycylindrical region wherein droplets of mist and foam separated from thegas flow travel downwardly toward the drain with reduced resistance fromthe counter flowing gas. This improves mist and foam separation from themixture.

At the downstream, outlet end of the housing, a vortex finder tube 125is secured to the frusto-conical end 128 of the outlet. The outlet 104communicates with return line 258 to return gas (usually air) to theblower 256 (FIG. 2). Flow rate is controlled via valve 78.

In accordance with the invention, a first cyclonic action zone 150 isprovided in the cylindrical housing between the baffle 106 and the vaneassembly 108. In addition, a second cyclonic action zone 152 is providedin the housing between the assembly 108 and the outlet 104. In practice,it has been found that the first and second cyclonic action zones shouldbe approximate equal volume.

In one field application of the mist eliminator disposed as shown in thesuction box receptacle of an Ericsson type washer, substantial amountsof the dense foam floating along the liquor level were desirably drawninto the zone 150 for preliminary separation therein. After this initialseparation, the gas/liquid mixture was further separated in the secondcyclonic action zone 152. Location of the vane assembly 108 at agenerally medial disposition within the housing provides a more elevatedposition that in some of the prior art devices and thereby increaseshead pressure over the opening 122 to improve liquid drainage thru tube124.

In another aspect of the invention, the improved separation device isused to separate ink particles from a recycled fiber slurry. In typicaldeinking applications recycled fibers including mixed office waste, andold newsprint etc., are commonly fiberized in a hydrapulper or the likein the presence of chemical additives that are adapted to facilitateseparation of the ink particles from the pulp. The ink particles thatare dislodged are released from the fiber surfaces due to mechanicaland/or chemical reaction are separated from the slurry via dispersion,washing and flotation processes.

The separator 50 of the invention may be ideally used in deinking cellsto aid in separation of ink particles from the recycle pulp. In suchcells, air bubble generators or the like, with or without chemicalflotation enhancement agents, are provided in a cell or series of cellsin which the particles are released from the fibers and are carried tothe slurry surface. The particles normally float atop the surface in afoamy mass.

Turning to FIG. 6 of the drawings, there is shown deinking cell 200 ofthe type normally encountered in deinking processes. As shown, the cellincludes an agitator 202 to promote air bubble formation. The inkparticles are floated in the form of a dense foamy mass 204 atop therecycle pulp slurry 206. The separator 50 is spaced over the foam 204. Asuction line 210 is connected to the outlet 104 of the separator. Inthis embodiment, the air straightening baffle normally positionedadjacent the separator inlet is omitted. It is noted that although onlyone separator 50 is depicted in the drawings, a bank or plurality of thesame may actually be employed in conjunction with a deinking cell.

In operation, the vacuum drawn through the line 210 picks the dense mass204 off the top of the recycle pulp slurry. The foamy mass 204 entersthe first cyclonic zone 150 where it is subjected to a preliminaryseparation, then moving downstream through the vanes and into the secondcyclonic action zone 152. The ink particles are lower in specificgravity than the liquid so the cyclonic action causes same to beseparated and removed through line 210.

While the form of apparatus herein described constitutes a preferredembodiment of this invention, it is to be understood that the inventionis not limited to this precise form of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:
 1. Cyclonic separation device for separation ofliquid from a gas and liquid containing stream flowing from an upstreamto downstream direction in said device, said separation devicecomprising a cylindrical housing having a longitudinally disposed axisextending thru said housing, an inlet end and an outlet end disposed atopposing ends of said cylindrical housing and a cyclonic flow inducingvane assembly positioned at an intermediate location along saidlongitudinal axis and defining a first cyclonic separation zone withinsaid housing upstream from said vane assembly, and a second cyclonicseparation zone within said housing downstream from said vane assembly.2. Cyclonic separation device is recited in claim 1 further comprising agenerally cylindrical vane assembly shroud surrounding said vaneassembly and coaxially disposed within said cylindrical housing. 3.Cyclonic separation device as recited in claim 2 further comprising anannular rim surrounding said shroud and contiguous with said housing toform an airtight barrier in said housing, said rim being disposed at aninclined angle relative to said longitudinal axis, said rim compromisingan opening therein located at a portion of said rim spaced more closelyto said inlet than other rim portions for allowing draining liquid flowtherethrough.
 4. Cyclonic separator as recited in claim 3 furthercomprising a drain tube connected to said opening for draining liquidfrom said housing.
 5. Cyclonic separator as recited in claim 3 furthercomprising a flow straightening baffle assembly located in said housingproximate e said inlet, said first cyclonic separation zone located insaid housing between said rim and said flow straightening baffleassembly.
 6. Cyclonic separator as recited in claim 5 further comprisinga vortex finder located proximate said outlet end, said vortex findercomprising a tube disposed along said longitudinal axis, said outlet endof said cylinder including a cap with said vortex tube depending fromsaid cap and terminating in an outlet opening in said cap, said secondcyclonic separation zone located between said rim and said cap. 7.Cyclonic separator as recited in claim 2 wherein said vane assemblycomprises a rod extending longitudinally in said shroud, and at leastone spiral flight extending around at least a portion of said rod, saidflight connected to said shroud.
 8. Cyclonic separator as recited inclaim 7 wherein said vane assembly comprises a first and second spiralscrew flight.
 9. Cyclonic separator as recited in claim 1 wherein saidfirst and second cyclonic separation zones are of approximate equalvolume.
 10. In combination with a suction box of a pulp washer orthickener wherein a level of liquid is disposed within said suction box,a gas/liquid separator device, said gas/liquid separator devicecomprising a cylindrical housing disposed above said liquid level, saidhousing having a longitudinally disposed axis extending therethrough andan inlet end and an outlet end disposed at opposing ends of saidhousing, said outlet end being in communication with a suction source todraw a mixture of gas and liquid through said gas/liquid separatordevice from an upstream to downstream direction for separation of saidliquid and said gas; said gas/liquid separator device further comprisinga cyclonic flow inducing vane assembly positioned at an intermediatelocation along said longitudinal axis and defining a first cyclonicseparation zone located in said housing upstream from said vane assemblyand a second cyclonic separation zone in said housing downstream fromsaid vane assembly.
 11. Combination as recited in claim 10 furthercomprising a vane assembly shroud surrounding said vane assembly andcoaxially disposed within said cylindrical housing.
 12. Combination asrecited in claim 11 further comprising an annular rim surrounding saidshroud and contiguous with said housing to form an airtight barrier insaid housing, said rim disposed at an inclined angle relative to saidlongitudinal axis, said rim comprising an opening therein at a portionof said rim spaced more closely to said inlet than other portions ofsaid rim for allowing drainage of liquid from said second cyclonicseparation zone.
 13. Combination as recited in claim 12 furthercomprising a drain tube extending from said opening to said liquid withsaid suction box.
 14. Combination as recited in claim 13 furthercomprising a flow straightening baffle assembly located in said housingproximate said inlet, said first cyclonic separation zone located insaid housing between said rim and said flow straightening baffleassembly.
 15. Combination as recited in claim 14 further comprising avortex finder located proximate said outlet end, said vortex findercomprising a tube disposed along said longitudinal axis, said outlet endof said cylinder including a cap with said vortex tube depending fromsaid cap and terminating in an outlet opening in said cap, said secondcyclonic separation zone located between said rim and said cap. 16.Combination as recited in claim 15 where in said vane assembly comprisesa rod extending longitudinally in said shroud, and at least one spiralflight extending around at least a portion of said rod.
 17. Combinationas recited in claim 16 where in said vane assembly comprises a fir andsecond spiral screw flight.
 18. Combination as recited in claim 10wherein said first and second cyclonic separation zones are ofapproximate equal volume.
 19. In a pulp washer of the type having ahorizontally disposed endless wire, drive means for moving said wirefrom an upstream to downstream location on said wire, headbox means forfeeding a pulp suspension to an upstream location on said wire, asuction box receptacle underlying said wire, water shower meanspositioned over said wire for directing a water shower over said wireand said pulp to wash said pulp whereby some of said water will draininto said suction box receptacle, and vacuum system means for creatingsuction under said wire to augment flow of wash water through said wireto said suction box receptacle; the improvement comprising a water/gasseparator positioned proximate said suction box and draining liquid intosaid suction box, said separator comprising a cylindrical housing havinga longitudinal axis extending therethrough and an inlet end and anoutlet end disposed at opposing ends of said housing, said outlet endbeing in communication with said vacuum system means to draw a mixtureof said water and gas from said suction box receptacle through saidwater/gas separator device from an upstream to downstream direction forseparating said water and said gas, said water/gas separator devicefurther comprising a cyclonic flow inducing vane assembly positioned atan intermediate location along said longitudinal axis and defining afirst cyclonic separation zone located in said housing upstream fromsaid vane assembly and a second cyclonic separation zone in said housingdownstream from said vane assembly.
 20. In a deinking cell wherein inkparticles are floated in a foamy mass on top of a fiber containingslurry for separation from said slurry, a cyclonic separation apparatusfor separating said floated particles from said fiber slurry, saidcyclonic separation apparatus comprising a cylindrical housing having alongitudinal axis extending therethrough and an inlet end and an outletend disposed at opposing ends of said housing, said outlet end adaptedfor communication with said suction source for drawing said foamy masscontaining said ink particles from said deinking cell through saidcyclonic separation apparatus from an upstream to a downstreamdirection, said cyclonic separation apparatus further comprising acyclonic flow inducing vane assembly positioned at an intermediatelocation along said longitudinal axis and defining a first cyclonicseparation zone located in said housing upstream from said vane assemblyand a second cyclonic separation zone in said housing downstream fromsaid vane assembly.
 21. Cyclonic separation apparatus as recited inclaim 20 further comprising a vane assembly shroud surrounding said vaneassembly and coaxially disposed within said cylindrical housing. 22.Cyclonic separation apparatus as recited in claim 21 further comprisingan annular rim surrounding said shroud and contiguous with said housingto form an airtight barrier in said housing, said rim disposed at aninclined angle relative to said longitudinal axis, said rim comprisingan opening therein at a portion of said rim spaced more closely to saidinlet than other portions of said rim for allowing drainage of liquidfrom said second cyclonic separation zone.
 23. Cyclonic separationapparatus as recited in claim 22 further comprising a drain tubeextending from said opening to said slurry.
 24. Cyclonic separationapparatus as recited in claim 23 wherein said vane assembly comprises arod extending longitudinally in said shroud, and at least one spiralflight extending around at least a portion of the circumference of saidrod.
 25. Cyclonic separation apparatus as recited in claim 24 whereinsaid vane assembly comprises a first and second spiral screw flight. 26.Cyclonic separation apparatus as recited in claim 20 wherein said firstand second cyclonic separation zones are of approximate equal volume.27. Method for separating liquids existing in a gas stream in aprocessing apparatus of the type having a suction box receptacle with areservoir of liquid disposed therein, said method comprising; (1)providing a gas/liquid separator including a generally cylindricalhousing, a gas/liquid inlet and a gas outlet disposed at opposing endsof said housing and tandem first and second cyclonic separation zones insaid housing, (2) positioning said gas/liquid separator proximate saidsuction box receptacle; (3) drawing said gas stream through said firstcyclonic separation zone and then through said second cyclonicseparation zone; and (4) draining liquids from said separator into saidreservoir of liquid.
 28. Method for separating ink particles from afiber containing slurry wherein said ink particles are floated in afoamy mass on top of said slurry comprising the steps of; (1) drawingsaid foamy mass containing said ink particles off of said slurry andinto a first cyclonic action zone; and then (2) forwarding said foamymist from said first cyclonic action zone into a second cyclonic actionzone whereby said foamy mist is separated into an ink and liquidcomponent fraction and a lighter air fraction.
 29. Method as recited inclaim 28 wherein said steps (1) and (2) are both performed within asingle cyclone assembly unit.
 30. Method as recited in claim 29 whereinsaid first and second cyclonic action zones are of approximate equalvolume.